Subaru EA82T Specifications
| Engine Model: Subaru EA82T |
| Engine Type: 4-cycle 4-cylinder SOHC 8-valve turbocharged liquid-cooled gasoline |
| Total Displacement: 108.7 cu.in (1.78 L) |
| Rated Engine Power: 115-135 Hp (86-100 kW) at 5600 rpm |
| Fuel System Type: Multi-point electronic fuel injection |
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The Subaru EA82T is a 1.8-liter turbocharged flat-four
engine produced between 1984 and 1990, representing the performance-oriented
culmination of Subaru’s EA series before the transition to the EJ family.
Derived from the naturally aspirated EA82, the EA82T incorporated multi-port
fuel injection, a single overhead camshaft per cylinder bank, and a water-cooled
turbocharger to deliver power outputs ranging from 115 to 136 hp depending on
market and intake manifold configuration.
The engine retained the distinctive horizontally opposed architecture with
aluminum block and cylinder heads, a configuration that lowered the center of
gravity and contributed to Subaru’s all-wheel drive vehicles’ handling
characteristics. The EA82T powered flagship models including the GL-10, RX
Turbo, and XT Turbo, serving as Subaru’s performance engine in the pre-EJ era.
Its design featured a unique cylinder head layout with dual intake ports and a
single exhaust port per bank, dished pistons with a reduced compression ratio of
7.7:1 to accommodate forced induction, and hydraulic lash adjusters that became
a characteristic feature of the EA series. The engine gained recognition for its
durability under rally competition while acquiring a reputation for cylinder
head cracking and cooling system sensitivity.
Engine Type: 4-stroke, horizontally opposed 4-cylinder (flat-four), turbo
gasoline engine.
Displacement: 1,781 cc (1.8 L; 108.7 cu.in).
Bore: 92.0 mm (3.622 in).
Stroke: 67.0 mm (2.638 in).
Compression Ratio: 7.7:1.
Firing Order: 1-3-2-4.
Valvetrain: SOHC, 8 valves total, timing belt drive, hydraulic lash adjusters.
Combustion Chamber: Wedge-type with single exhaust port per cylinder bank.
Aspiration: Single water-cooled turbocharger with integral wastegate, air-to-air
intercooler on selected variants.
Maximum Boost Pressure: 48-55 kPa (7.0-8.0 psi) relative, regulated by internal
wastegate.
Maximum Engine Speed: 6,500 rpm (governed).
North American Market (GL-10, RX)
Maximum Power: 86-97 kW (115-130 hp; 117-132 PS) at 5,200-5,600 rpm.
Maximum Torque: 178-196 Nm (131-145 lb-ft) at 2,800-3,200 rpm.
Japanese Domestic Market (RX, XT Turbo)
Maximum Power: 100-101 kW (135-136 hp; 137-138 PS) at 5,600 rpm.
Maximum Torque: 185-196 Nm (136-145 lb-ft) at 3,200 rpm.
Compression Pressure
Standard: 1.15-1.35 MPa (167-196 psi).
Minimum service limit: 0.95 MPa (138 psi).
Maximum permissible variation between cylinders: 0.10 MPa (15 psi).
The cylinder block is constructed from aluminum alloy
with cast-in iron cylinder liners, utilizing Subaru’s horizontally opposed
architecture where the two banks of cylinders face each other at 180 degrees.
The block is split along the crankshaft centerline, with an upper block and
lower bedplate assembly that secures the crankshaft main bearings. Five main
bearings support the cast iron crankshaft.
The cylinder liners are machined to a plateau-honed finish after casting. The
block incorporates an integral oil gallery network and coolant passages
surrounding each cylinder. The engine mounts are positioned on the sides of the
block to accommodate the low-profile flat configuration. The turbocharger
mounting provisions include dedicated oil return passages and coolant supply
ports on the passenger-side cylinder bank.
Each cylinder bank receives an aluminum alloy cylinder
head with a wedge-style combustion chamber. The EA82T heads are distinct from
naturally aspirated EA82 variants, featuring a revised combustion chamber volume
to achieve the 7.7:1 compression ratio and additional oil and coolant passages
on the passenger-side head to supply the turbocharger.
Each head incorporates a single overhead camshaft supported by four bearing
journals, actuating two valves per cylinder through rocker arms with hydraulic
lash adjusters. The intake ports are configured as dual passages per cylinder,
while the exhaust port is a single passage per bank merging into a common
exhaust manifold flange. The hydraulic lash adjusters, known as HLAs, maintain
zero valve clearance automatically but are sensitive to oil quality and
aeration.
Number of Valves: 8 total (2 per cylinder)
Intake Valve Diameter: 36.0 mm (1.417 in)
Exhaust Valve Diameter: 31.0 mm (1.220 in)
Valve Stem Diameter: 8.0 mm (0.315 in) for both intake and exhaust
Valve Seat Inserts: Induction-hardened seats machined directly into the cylinder
head
Valve Clearance: Hydraulic lash adjusters; no manual adjustment required
Valve Timing (nominal)
Intake Opens: 10° BTDC
Intake Closes: 50° ABDC
Exhaust Opens: 50° BBDC
Exhaust Closes: 10° ATDC
The fuel system employs a multi-point electronic fuel
injection (MPFI) system with sequential or semi-sequential injection timing
depending on the engine control unit variant. A high-pressure in-tank electric
fuel pump delivers fuel through a stainless steel fuel rail. Two intake manifold
configurations were produced. The standard MPFI manifold, used on GL-10 and RX
models, features a compact plenum with short runners.
The performance "Spider" manifold, found on XT Turbo and JDM high-output
variants, incorporates longer intake runners and a larger plenum volume to
improve mid-range torque and high-rpm breathing. A vacuum-referenced fuel
pressure regulator maintains a constant pressure differential across the
injectors.
Injectors: Side-feed, high-impedance; flow rate of 240-280 cc/min at 300 kPa
base pressure.
Fuel Filtration: In-tank primary strainer and replaceable inline filter rated at
10 microns.
Fuel Pressure (with vacuum line disconnected): 280-320 kPa (41-46 psi).
Fuel Specification: Premium unleaded 95 RON minimum for turbocharged variants.
The lubrication system utilizes a gear-type oil pump
mounted to the front of the cylinder block and driven by the crankshaft. The
pump draws oil from a baffled steel sump through a strainer screen and delivers
it to a full-flow disposable cartridge oil filter mounted on the side of the
block. A water-cooled oil cooler is integrated on turbocharged variants to
maintain oil temperature under sustained boost.
The system incorporates a pressure relief valve calibrated to maintain stable
pressure. Main galleries distribute oil to the crankshaft main bearings,
connecting rod bearings, camshaft bearings, and hydraulic lash adjusters. The
turbocharger receives oil through a dedicated supply line from the
passenger-side cylinder head, with oil returning to the block through a gravity
drain line.
Oil Pump Type: Gear-type, crankshaft-driven.
Oil Pressure (hot, at 3,000 rpm): 300-400 kPa (44-58 psi).
Oil Pressure (hot, idle): 70 kPa (10 psi) minimum.
Oil Capacity (with filter): 4.5 L (4.8 US qt).
Oil Specification: API SF, SG, or higher; SAE 10W-30 for most climates; SAE
20W-50 for sustained high ambient temperatures above 30 °C (86 °F) or track use.
The cooling system employs a belt-driven centrifugal
water pump mounted to the front of the engine block. Coolant flows from the
radiator through the pump, then through the cylinder block water jacket, upward
into the cylinder heads, and returns to the radiator through a thermostat
housing located at the front of the intake manifold. A wax-pellet thermostat
with a bypass circuit maintains operating temperature stability.
The system incorporates a cross-flow aluminum radiator with a pressure-type
filler cap rated at 88-108 kPa (13-16 psi). A dedicated coolant circuit serves
the turbocharger bearing housing, with coolant circulating through the water
pump and thermostat housing. The EA82T is sensitive to cooling system integrity;
cylinder head cracking between the intake and exhaust valves is a known failure
mode following overheating events.
Water Pump Type: Belt-driven centrifugal pump with cast iron housing and stamped
steel impeller. Coolant Capacity (engine and radiator): 6.5-7.5 L (6.9-7.9 US
qt) depending on heater core and turbocharger cooling configuration. Thermostat
Opening Temperature: 82 °C (180 °F). Thermostat Fully Open Temperature: 95 °C
(203 °F). Coolant Specification: Ethylene-glycol based with aluminum-compatible
corrosion inhibitors; 50% concentration.
| Intake and Exhaust Systems |
Intake System: Air enters through a paper-element air
cleaner housing, passes through the turbocharger compressor, then through an
air-to-air intercooler on selected variants (XT Turbo, JDM RX). The intercooler
is mounted above the engine with a ducted hood scoop. Non-intercooled variants
route compressed air directly to the throttle body. The intake manifold
incorporates a throttle body with an idle air control valve and throttle
position sensor. The Spider intake manifold, used on higher-output variants,
features longer runners and a tuned plenum volume optimized for performance.
Exhaust System: Cast iron exhaust manifold with separate passages for each
cylinder bank merging into a single turbocharger inlet flange. The manifold
incorporates expansion joints to accommodate thermal cycling. The system
includes a catalytic converter and a single underfloor muffler.
| Ignition and Electrical System |
Ignition System: Distributor-type ignition system with
an optical or magnetic crank angle sensor integrated into the distributor
assembly. The distributor is driven by the driver-side camshaft. Ignition timing
is controlled by the engine control unit with mechanical and vacuum advance
functions on earlier variants. A knock sensor is incorporated on later models to
allow timing retard under detonation conditions.
Electrical System: 12V negative-ground electrical architecture. Starter motor is
mounted to the transmission bellhousing. Alternator output is 60 A or 75 A
depending on vehicle specification. Engine control unit is a Hitachi or JECS
unit with fuel injection and ignition control.
The EA82T employs a water-cooled IHI RHB5 or VF7
turbocharger with an integral wastegate. The turbine housing is cast iron, while
the compressor housing is aluminum. The wastegate actuator is set to open at
approximately 48-55 kPa (7.0-8.0 psi). The turbocharger is mounted low on the
passenger side of the engine, positioned near the inner CV joint, requiring heat
shielding to prevent axle boot damage.
Length (front of accessory drive to rear of flywheel
housing): 680 mm (26.8 in).
Width (overall, across cylinder heads): 710 mm (28.0 in).
Height (from oil pan rail to top of intake manifold): 580 mm (22.8 in).
Dry Weight (complete engine with flywheel, turbocharger, and manifolds): 145 kg
(320 lb).
Dry Weight (complete engine with alternator, starter, and accessories): 158 kg
(348 lb).
Engine Oil: API SF, SG, or higher; SAE 10W-30, SAE
20W-50.
Oil Change Interval: 5,000 km (3,100 mi) for severe service.
Oil Change Interval: 7,500 km (4,700 mi) for normal highway operation.
Oil Filter Replacement: Every oil change; use OEM or equivalent high-efficiency
filter.
Coolant Capacity: 6.5-7.5 L (6.9-7.9 US qt).
Coolant Change Interval: 24,000 km (15,000 mi) or 24 months.
Fuel Filter Replacement: 30,000 km (18,600 mi).
Air Filter Replacement: 20,000 km (12,400 mi); more frequent under dusty
conditions.
Timing Belt Replacement: 100,000 km (62,000 mi) or 60 months.
Valve Clearance: Hydraulic lash adjusters; no adjustment required.
Spark Plugs: NGK BPR6ES or equivalent copper core; gap: 0.8-0.9 mm (0.031-0.035
in).
Spark Plug Replacement Interval: 20,000 km (12,400 mi) for copper core.
Idle Speed (closed throttle, transmission in neutral): 750-850 rpm.
Drive Belt Tension: Manual adjustment; deflection of 10-12 mm (0.39-0.47 in).
Cylinder Head Bolts (M11), Stage 1: 30 Nm (22 lb-ft)
Cylinder Head Bolts (M11), Stage 2: 50 Nm (37 lb-ft)
Cylinder Head Bolts (M11), Stage 3: 70 Nm (52 lb-ft)
Main Bearing Cap Bolts (M12), Stage 1: 30 Nm (22 lb-ft)
Main Bearing Cap Bolts (M12), Stage 2: 50 Nm (37 lb-ft)
Main Bearing Cap Bolts (M12), Stage 3: 70 Nm (52 lb-ft)
Connecting Rod Cap Bolts (M9): 45-50 Nm (33-37 lb-ft)
Flywheel / Flexplate Bolts (M12): 70-80 Nm (52-59 lb-ft)
Camshaft Bearing Caps (M8): 18-22 Nm (13-16 lb-ft)
Camshaft Sprocket Bolts (M10): 50-60 Nm (37-44 lb-ft)
Timing Belt Tensioner Bolt: 40-45 Nm (30-33 lb-ft)
Intake Manifold Bolts (M8): 18-22 Nm (13-16 lb-ft)
Exhaust Manifold Bolts (M10): 35-40 Nm (26-30 lb-ft)
Turbocharger to Exhaust Manifold (M10): 40-45 Nm (30-33 lb-ft)
Turbocharger Oil Feed Line (M10): 25-30 Nm (18-22 lb-ft)
Turbocharger Coolant Line (M10): 25-30 Nm (18-22 lb-ft)
Valve Cover Bolts (M6): 5-7 Nm (4-5 lb-ft)
Oil Pan Bolts (M6): 6-8 Nm (4-6 lb-ft)
Oil Pump Mounting Bolts (M8): 18-22 Nm (13-16 lb-ft)
Water Pump Bolts (M8): 18-22 Nm (13-16 lb-ft)
Thermostat Housing Bolts (M8): 18-22 Nm (13-16 lb-ft)
Spark Plugs: 25-30 Nm (18-22 lb-ft)
Engine Mount Bracket to Block (M10): 40-50 Nm (30-37 lb-ft)
Crankshaft Pulley Bolt (M16): 150-170 Nm (111-125 lb-ft)
Alternator Mounting Bolts (M10): 35-40 Nm (26-30 lb-ft)
Starter Motor Mounting Bolts (M10): 40-45 Nm (30-33 lb-ft)
Subaru Leone / L-Series: 1984-1989 model years; GL-10
trim with EA82T engine in sedan, wagon, and three-door coupe body styles; RX
Turbo variant with performance suspension and full-time all-wheel drive.
Subaru XT / XT6 / Alcyone / Vortex: 1985-1991 model years; XT Turbo with EA82T
engine; JDM Vortex variant received the Spider intake manifold and intercooler
with higher output.
Subaru RX Coupe: 1985-1989; homologation special based on the Leone coupe; EA82T
with close-ratio transmission and full-time all-wheel drive; produced for Group
A rally competition.
Subaru GL-10: 1984-1989; premium trim level across Leone and L-Series models
featuring EA82T with standard MPFI manifold and digital instrumentation.
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